With growth of user requirements and development of communications technologies, types of wireless communications technologies and related networks are increasing, for example, 2G, 3G, and 4G mobile communications technologies and networks that can provide wide coverage, and a Wireless Fidelity (WiFi) technology and a wireless local area network (WLAN) that can provide hotspot coverage. Therefore, a large quantity of scenarios in which different communications networks coexist have emerged, for example, a scenario in which 2G, 3G, and 4G networks and a WLAN coexist.
An evolved packet system (EPS) system is a system that supports multiple access technologies and mobility between multiple access networks. In a multi-access scenario, a terminal may be in common coverage of multiple 3rd Generation Partnership Project (3GPP) and/or non-3GPP access networks. These access networks may use different access technologies, may belong to different operators, and may provide access to different core networks. FIG. 1 shows a scenario in which Universal Mobile Telecommunications System (UMTS)/Long Term Evolution (LTE) and WLAN networks coexist. In a coverage area of a base station of the UMTS/LTE (a Node B in the UMTS and an eNB in the LTE), multiple WLAN access point (AP) exist. Compared with a base station, coverage area of an access point is relatively small.
In the foregoing scenario, a network architecture for interoperation between the UMTS/LTE and the WLAN has already been supported. In the architecture, interoperation is implemented based on an S2c interface between a packet data network (PDN) Gateway and UE. In the prior art, the interoperation between the UMTS/LTE and the WLAN is implemented by using a terminal-based (UE based) solution.
With rapid development of intelligent terminals and mobile applications, mobile data traffic is increasing sharply, so that a current network is hardly to meet a requirement of increasing data traffic. Therefore, to alleviate traffic load of a current 3GPP network, mobile operators hope to use a non-3GPP network to carry a part of traffic of the 3GPP network.
Currently, when handover is performed on a terminal, after the handover, a destination base station selects, from APs under the destination base station, a destination AP that can perform service offloading, and sends information about the destination AP to the terminal. After the handover is performed on the terminal, a service of the terminal under a source base station is interrupted. Therefore, the terminal can access the destination AP and recover the service only after the destination base station sends the information about the destination AP to the terminal, and a service interruption period is relatively long. Consequently, service continuity is relatively poor, and service quality is relatively poor.